1. Field of the Invention
This invention relates to compositions of room temperature curing, elastomeric, silicone water-based emulsions, froth stabilizers, and aerosol propellants packaged under superatmospheric pressure which convert to an open-cell foam when released to atmospheric pressure and dried.
2. Background Information
Bengtson, in U.S. Pat. No. 3,830,760, issued Aug. 20, 1974, discloses a process for the manufacture of a foamable composition which comprises forming a mixture of a polymer or polymer precursor, curable on contact with the atmosphere, and a polymer soluble inert blowing agent under pressure. His broad list of polymers includes silicone. His examples show polyurethanes which are mixed and then transferred to aerosol containers. Dispensing the ingredients from the container yields a froth which then cures from exposure to the atmosphere to produce a closed-cell foam.
Sands, in patent application Ser. No. 391,899, filed June 25, 1982, assigned to the assignee of the instant application, discloses a method of producing a silicone elastomeric foam from an aqueous silicone emulsion suitable to provide an elastomeric product upon removal of the water. He mechanically generates a stable froth, then removes the water to form a cured elastomeric foam. He teaches drying by placing in an oven or air drying. Lee et al. in U.S. Pat. No. 4,391,765, issued July 5, 1983, teach a simplified method of manufacturing a silicone elastomeric foam comprising mechanically generating a stable froth of an aqueous emulsion, while adding surfactant and thickener, then exposing the stable froth to microwave energy to remove the water. Johnson, in U.S. Pat. No. 4,391,921, issued July 5, 1983, disclose a method of producing open-cell sponge by freezing a silicone emulsion, thawing the frozen article, and drying until the water is removed.
Hagen et al. in German OLS No. 2,909,443, published Sept. 18, 1980, disclose a process for preparing a room temperature curing silicone foam. A one-component silicone material is mixed with a low boiling solvent and placed in a bag in a pressure package. A surface pressure, acting on the bag, squeezes the mixture out through a valve to form the foam.
Sattlegger et al. in U.S. Pat. No. 4,229,548, issued Oct. 21, 1980, describe a process of producing a foam. A hydroxyl endblocked polydiorganosiloxane and silicon-containing crosslinking agent are placed into the inner container of a two-container pack. The mixture may also contain a gas. The inner flexible container is then placed under pressure by pressurizing the space between the inner and outer containers. Upon opening the valve, the contents form a uniform closed cell foam, which then cures.